A study by Oxford University has revealed that a longer delay of up to 45 weeks between the first and second dose of the Oxford-AstraZeneca vaccine leads to enhanced immune response after the second dose.
A third dose given more than 6 months after the second dose leads to a substantial increase in antibodies and induces a strong boost to immune response against COVID-19, including variants.
This research included examining the effects of a delay of up to 45 weeks between first and second doses in study participants.
The announcement of this development comes at a time when COVID-19 vaccine supply shortage has caused concerns in some countries about compromised immunity as the interval between first and second dose extends due to limited vaccine availability.
“This should come as reassuring news to countries with lower supplies of the vaccine, who may be concerned about delays in providing second doses to their populations.” Sir Andrew Pollard, Professor of Paediatric Infection and Immunity and Lead Investigator of the Oxford University trial of the vaccine said.
Adding that there is an excellent response to a second dose, even after a 10-month delay from the first.
The report by Oxford University also stated that some countries are considering administering a third ‘booster’ dose in the future.
Studying the impact of a third vaccine dose, the researchers found that antibody titres increased significantly with a third dose. T-cell response and the immune response against variants were also boosted.
“It is not known if booster jabs will be needed due to waning immunity or to augment immunity against variants of concern,” said Associate Professor Teresa Lambe OBE.
(With input from University of Oxford)
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